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|Title: ||Phase manipulation and its applications in microwave circuits|
|Other Titles: ||Xiang wei kong zhi ji qi zai wei bo dian lu zhong de ying yong|
|Authors: ||Wong, Ka Wai (王嘉煒)|
|Department: ||Department of Electronic Engineering|
|Degree: ||Master of Philosophy|
|Issue Date: ||2009|
|Publisher: ||City University of Hong Kong|
|Subjects: ||Microwave circuits.|
|Notes: ||CityU Call Number: TK7876 .W637 2009|
ix, 91 leaves : ill. 30 cm.
Thesis (M.Phil.)--City University of Hong Kong, 2009.
Includes bibliographical references.
|Abstract: ||The wireless industry has been boosted over the decades. A lot of wireless
applications are shifting to the higher frequency bands, which make the phase of a
microwave signal more significant for the proper application of the whole circuits.
Hence, it is valuable to investigate the issues of the phase manipulation in some of the
microwave circuits such as antenna, active and passive components.
This dissertation investigates three phase techniques namely the phase
conjugation, phase inversion and phase combination/cancellation. By using these
approaches of the phase manipulation effectively, some novel wideband or dual-band
circuits are accomplished. An antenna array and some microwave components such as
power divider, wideband bandpass filter and the dual-band bandstop filter are then
proposed and analyzed in details.
To begin with, a 2-dimensional phase-conjugating retrodirective array using the
star-shaped antenna element is proposed. This 2-D cross-shaped antenna array which
employed the low-conversion loss phase-conjugating mixer is able to achieve a good
retrodirectivity with wide scan range of 120°. Our proposed dual-fed star-shaped
antenna element is proposed for lowering the mutual coupling between the antenna
elements. Furthermore, the antenna array is able to support the linear or circular
polarization signals and the information carrying capability is demonstrated
experimentally as well. Secondly, the phase inversion technique is used to implement two circuits. One is
a two-way power divider with very wide isolation bandwidth and the other is a new
type of wideband bandpass filter with a flat group delay. In the proposed power
divider, the 20-dB isolation bandwidth is more than 160%. Experimental results also
show that the fractional bandwidths are more than 50%, on the conditions of 20 dB
return loss, less than 3.3 dB insertion loss (3 dB for ideal coupling) and 3° phase
imbalance. As for the proposed wideband bandpass filter, the measured fractional
passband bandwidth is 123% with a flat group delay response. Furthermore, over 90%
impedance bandwidth is obtained for the return loss higher than 20 dB. The
theoretical simulation, electromagnetic simulation, and measured results all show
good agreement with this proposed design.
Finally, a simple non-resonating dual-band bandstop filter using the technique of
phase combination/cancellation is proposed. A prototype is demonstrated for
eliminating the 2.4/5.8-GHz ISM applications. The measured results indicate that the
dual fractional stopband bandwidths with 20-dB signal attenuation are 25.2% and
12.4%. Also, the theoretical simulation, electromagnetic simulation and measured
results all show good agreement with this simple design. This design concept can also
be easily applied to further implementation of the millimeter-wave filter by the same
design flow. Detailed information for finding the exact transmission poles and zeros
are discussed in this section.|
|Online Catalog Link: ||http://lib.cityu.edu.hk/record=b2375044|
|Appears in Collections:||EE - Master of Philosophy |
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